The present invention relates generally to construction materials and processes; and more particularly, it relates to the electrodeposition of minerals to repair damaged concrete structures having embedded metal reinforcement.
Seawater contains nine major elements: sodium, magnesium, calcium, potassium, strontium, chlorine, sulphur, bromine, and carbon. These elements comprise more than 99.9% of the total dissolved salts in the ocean (see Milliman, et al., Marine Carbonates, Springer-Verlag, N.Y., 1974; Sverdrup, et al., The Oceans: Their Physics, Chemistry, and General Biology, Prentiss-Hall, Inc., in N.J. 1942; and Culkin and Goldbert in Volume 1, Chemical Oceanography, pp. 121-196, Academic Press, London 1965). The constancy of the ratios of the major elements throughout the oceans has long been well-known (Dittmar, Challenger Reports, Physics and Chemistry, pp. 1-251, 1884).
In 1940 and 1947, G. C. Cox was issued U.S. Pat. Nos. 2,200,469 and 2,417,064, outlining methods of cathodic cleaning and protection of metallic surfaces submerged in seawater by means of a direct electrical current. During the cleaning process, a coating is also formed cathodically, consisting of magnesium and calcium salts (Eickhoff and Shaw, Corrosion, No. 4, pp. 463-474, 1948). If these coatings are hard and continuous, they afford a considerable degree of corrosion protection to the enclosed metal (see Humble, Corrosion, No. 4, pp. 358-370, 1948, and Corrosion, Volume 4, No. 9, pp. 292-302, 1949)
Lower marine organisms utilize the minerals in solutions surrounding them to build structural formations. Mollusk shells, for example, are generally composed of calcium carbonate crystals enclosed in an organic matrix. A significant proportion of the soluble protein in the matrix is composed of a repeating sequence of aspartic acid separated by either glycine or serine (see Jope in Volume 26, Comprehensive Biochemistry, p. 749, Elsevier, Amsterdam, 1971). This sequence, comprising regular repeating negative charges, could bind Ca.sup.2+ ions and thus perform an important function in mineralization of the template (Weiner and Hood, Volume 190, Science, pp. 987-989, 1975).
In 1978, Wolf H. Hilbertz reported the feasibility of using electrodeposited minerals as a building material for building components. (Hilbertz, W. H., Electrodeposition of Minerals in Seawater, Oceans '78, pp. 699-706, 1978.)
The art fails, however, to teach the repair of imperfect or damaged reinforced concrete structures through electrochemical precipitation of minerals, which is referred to herein as "mineral accretion".